Boosting electrochemical CO2 reduction via valence state and oxygen vacancy controllable Bi-Sn/CeO2 nanorod.

Electrocatalytic CO2 reduction reaction (CO2RR) to produce formate has been recognized as one of the most efficient strategies to convert CO2 to energy-rich products and store renewable energy compared with other methods such as biological reduction, thermal catalytic reduction, and photocatalytic reduction. Developing an efficient catalyst is crucial to enhance the formate Faradaic efficiency (FEformate) and retard the competing H2 evolution reaction. The combination of Sn and Bi has been demonstrated to be effective in inhibiting the evolution of H2 and the generation of CO, promoting the formation of formate. Herein, we design Bi- and Sn-anchored CeO2 nanorods catalysts with the valence state and oxygen vacancy (Vo) concentration controllable for CO2RR by reduction treatment at different environments. The m-Bi1Sn2Ox/CeO2 with moderate H2 composition reduction and suitable Sn/Bi molar ratio achieves a remarkable FEformate of 87.7% at -1.18 V vs. RHE compared with other catalysts. Additionally, the selectivity of formate was maintained over 20 h with an outstanding FEformate of above 80% in 0.5 M KHCO3 electrolyte. The outstanding CO2RR performance was attributed to the highest surface Sn2+ concentration which improves the formate selectivity. Further, the electron delocalization effect between Bi, Sn, and CeO2 tunes electronic structure and Vo concentration, promoting the CO2 adsorption and activation as well as facilitating the formation of key intermediates HCOO* as evidenced by the in-situ Attenuated Total Reflectance-Fourier Transform Infrared measurements and Density Functional Theory calculations. This work provides an interesting measure for the rational design of efficient CO2RR catalysts via valence state and Vo concentration control.

Enhanced selective separation of vanadium(V) and chromium(VI) using the CeO2 nanorod containing oxygen vacancies.

Adsorption of vanadium from wastewater defends the environment from toxic ions and contributes to recover the valuable metal. However, it is still challenging for the separation of vanadium (V5+) and chromium (Cr6+) because of their similar properties. Herein, a kind of CeO2 nanorod containing oxygen vacancies is facilely synthesized which displays ultra-high selectivity of V5+ against various competitive ions (i.e., Fe, Mn, Cr, Ni, Cu, Zn, Ga, Cd, Ba, Pb, Mg, Be, and Co). Moreover, a large separation factor (SFV/Cr) of 114,169.14 for the selectivity of V5+ is achieved at the Cr6+/V5+ ratio of 80 with the trace amount of V5+ (~ 1 mg/L). The results show that the process of V5+ uptake is the monolayer homogeneous adsorption and is controlled by external and intraparticle diffusions. In addition, it also shows that V5+ is reduced to V3+ and V4+ and then formation of V-O complexation. This work offers a novel CeO2 nanorod material for efficient separation of V5+ and Cr6+ and also clarifies the mechanism of the V5+ adsorption on the CeO2 surface.

In situ synthesis of Cu nanoclusters/CeO2 nanorod as aggregated induced ECL probe for triple-negative breast cancer detection.

Cu nanoclusters (NCs) have attracted a lot of attention due to the excellent properties. However, the low luminescence and poor stability limited the Cu NC-based sensing research. In this work, Cu NCs were in situ synthesized on CeO2 nanorods. On the one hand, the aggregated induced electrochemiluminescence (AIECL) of Cu NCs has been observed on the CeO2 nanorods. On the other hand, the substrate of CeO2 nanorods acted as catalysis, which reduced the excitation potential and further enhanced the ECL signal of Cu NCs. It was noticed that CeO2 nanorods also greatly improved the stability of Cu NCs. The resulted high ECL signals of Cu NCs can be kept constant for several days. Furthermore, MXene nanosheets/Au NPs has been employed as electrode modification materials to construct the sensing platform to detect miRNA-585-3p in triple negative breast cancer tissues. Au NPs@MXene nanosheets not only enlarged the specific interface area of the electrodes and the number of reaction sites, but also modulated electron transfer to amplify the ECL signal of Cu NCs. The biosensor had a low detection limit (0.9 fM) and a wide linear range (1 fM to 1 µM) for the detection of miRNA-585-3p in the clinic tissues.

Facile construction of hierarchical Co3S4/CeO2 heterogeneous nanorod array on cobalt foam for electrocatalytic overall water splitting.

Herein, a hierarchical Co3S4/CeO2 nanorod array on cobalt foam (Co3S4/CeO2-CF) was successfully constructed via a facile one-step hydrothermal method. The fabrication of Co3S4/CeO2-CF was confirmed by X-ray diffraction, scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM). It is observed that CeO2 nanorod was fully covered with Co3S4 nanosheets, forming a hierarchical core-shell nanostructure. Furthermore, CeO2 and Co3S4 were doped with each other during the one-step hydrothermal process, forming a heterogeneous Co3S4/CeO2 nanostructure. Density functional theory (DFT) calculations suggest that the introduction of CeO2 in Co3S4 is effective in reducing the free energy barrier of OER process. To achieve current density of 10 mA cm-2, only small overpotentials of 74.9 mV and 213 mV are required for HER and OER in 1.0 M KOH solution, respectively. In particular, the Co3S4/CeO2-CF based electrolysis cell for overall water splitting only needs an output voltage of 1.64 V in the alkaline medium, lower than that of Pt/C-RuO2-based electrolysis cells (1.70 V). Such hierarchical heterogeneous catalyst also shows ultra-stable catalytic activity. Therefore, with the favorable heterointerfaces and hierarchical structures, Co3S4/CeO2-CF could be a promising bifunctional electrocatalyst for overall water splitting and this study may also provide a facile method for the preparation of hierarchical heterogeneous nanostructured materials.